Paracheirodon axelrodi or cardinalfish: related to piranha, but not at all aggressive. Let’s look at features, habitats, and nutrition.

Paracheirodon axelrodi or cardinal fish. (Adobe Stock)

Paracheirodon axelrodi or cardinal fish, is considered a practically annual fish, being very rare to find individuals over one year old, while in the aquarium it can live much longer.

It is a very sociable fish, ideal for community aquariums. He is very comfortable in groups of over six individuals. If the group has fewer than six individuals, can share the aquarium with Neon Tetra individuals, which have an important peculiarity for the cardinal fish, the neon tetra tends to close in a group if it feels the danger that in the case of the aquarium it could be the presence of larger fish.

Characteristics of Paracheirodon axelrodi or cardinal fish

Paracheirodon axelrodi or cardinal fish
Paracheirodon axelrodi or cardinal fish. (Adobe Stock)

The cardinal fish has a thin body, reaches a maximum length of 5 cm, torpedo-shaped with very bright colors. He has large eyes, which occupy half of the head. Two distinct blue and red lines cross each other horizontally.

The fins are transparent, including the tail and the fatty fin, characteristic of the Characids. It is often confused with neon, the only substantial difference lies in the fact that the latter has the red line that crosses the body only from the end of the belly up to the tail.

Adult females of Paracheirodon axelrodi tend to be more abundant than males and have a blue band on the sides of the body that tends to tilt upwards.

Habitat and reproduction of the cardinalfish

aquarium
Plant-rich aquarium (Pixabay photo)

Paracheirodon axelrodi can only be found in forest streams and minor tributaries with slow-flowing waters. Characterized by dense riparian vegetation, often overhanging, and with the substrate covered by fallen branches, tree roots, and a litter of fallen leaves.

Where the water is typically acidic, with conductivity and marginal carbonate hardness. The color is dark amber, due to the presence of decomposed organic matter. All this in the waters of the Rio Negro while in the Rio Orinoco basin the water is clear and transparent with a sandy substrate, often with a dense growth of aquatic plants or vegetation, among which fish take refuge.

The water is still acidic, although to a lesser extent than the Rio Negro. The Rio Negro river basin and the upper Orinoco basin are the only places where you can see this fish.

In any case, it is a seasonal habitat and indeed during the dry season fish tend to form large schools in the main channels of watercourses while with the arrival of the rains they undergo movements in the areas of flooded vegetation or looking for cover between the submerged roots.

This seasonal hydrological cycle also allows a mixture of the populations of cardinal tetras, which otherwise would remain isolated from each other. As for life in the aquarium, this fish needs 1 meter to be able to live well, as he is always on the move and is a skilled swimmer.

In fact, the aquarium must be left empty by plants for a good half. He does not like loneliness, he needs at least 10/15 specimens, with which it goes well and coexistence with fish bigger than them is absolutely to be avoided.

However, to see them swim on the bench in a synchronous way as it happens in the major streams during the dry season, it is necessary to go up both in size and in the number of specimens, going towards aquariums of 120-150 cm and schools of 30-40 specimens.

Regarding reproduction, each female lays around 500 eggs, they often lay their eggs in the middle of the night, when the lighting is poor. The eggs stick to the leaves of the aquatic vegetation. Once the male has fertilized the eggs, it is recommended to remove the pair as there is the cannibalism of the eggs.

After 36 hours the eggs hatch but the larvae are still unable to swim and this for 5 days. Their feeding will be administered with commercial products or egg yolk. Unfortunately, the reproduction of this species in captivity is very delicate since the young do not tolerate natural light well.

Feeding the Paracheirodon axelrodi

guppy feeding
Guppy feeding: how to feed the fry and adult fish (photo iStock)

Cardinalfish or Paracheirodon axelrodi is omnivorous and in nature, it feeds on small invertebrates, crustaceans, filamentous algae, fallen fruit and the like. In the aquarium, it can be fed with flake food, micro granules, live and frozen food such as mosquito larvae, Chironomus and daphnia.

A diet based only on dry fish feed, but like most fish it gets better when a varied menu is offered. Furthermore, it seems that in the diet of Paracheirodon axelrodi there is a lot of plant debris containing vegetable fibers, mushrooms, and fruit residues.

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